I have a 1999 sonoma with a 4.3L v6 (ends in X) that is 2wd with a regular cab and about 93k.

Recently, at highway speeds, the truck will jerk (not violently) almost as though the fuel is cutting out. As long as the accelerator is depressed, it doesn't seem to be as much of a problem but as soon as I let off the gas, it will begin to jerk - it's as though I am pushing down and letting off the gas pedal repeatedly.

Any thoughts would be appreciated.

maybe a dist cap...any codes?

no codes

changed distributor cap and rotor

have new plugs/wireset but haven't changed yet

i had a problem kinda like that and my temp sensor was messed up...you may also want to check the fuel to air ratio sensor

I had the same problem about 2months ago, its definetly something to do with your distributor. Could be the button or something else to do with it. unfortunetly GMC didn;t make there distributors like Chevies and there known to cause problems like yours. Its a quick 80$ repair at any backyard mechanic. Or 30$ if you do it yourself.